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Poll for brake guys - NOS caliper opinion UPDATE/photos
#312322
05/08/09 11:45 PM
05/08/09 11:45 PM
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Joined: Nov 2004
Posts: 9,312
SoCal
68HemiB
OP
master
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OP
master
Joined: Nov 2004
Posts: 9,312
SoCal
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Intelligent people can disagree.
My buddy and I do not share the same opinion on a pair of NOS F body calipers. The calipers are obviously unused, and the brake inlet is still capped. Take the cap off, and all looks pristine down the hole. There is some shelf rash and very light surface rusting. Dust boots are soft and intact. Nothing scary in the visual inspection.
The problem? Neither piston will budge upon application of compressed air with a rubber-tipped snozzle.
Person A: This is not good. These calipers are stuck. 2.75 inch piston diameter means 6 square inches of surface area (Pi are ROUND, Cornbread are square), which at 120psi air pressure means they won't budge with over 700 pounds of force. We need to get them apart, inspect them, and likely rebuild them.
Person B: Nice math, Archimedes. So how do you suggest we get the pistons UNstuck?
Person A: Well, as any professional knows, you hook them up to the vehicle's brake lines, bleed them, and then use the M.C.'s pressure advantange to get them pumped out.
Person B: So, we'll go to the trouble of doing all that, without even seeing if, once they get unstuck, they even hold pressure? Why don't we just do all that, but see if they hold pressure, can be pushed back, etc., BEFORE we tear them down.
Person A: But they're STUCK now. That means there's something wrong.
Person B: But if they free up, and don't leak...?
Person A: They are a problem waiting to happen.
Are you person A or B in this case?
Last edited by 68HemiB; 05/10/09 09:14 PM.
Down to just a blue car now.
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Re: Poll for brake guys - NOS caliper opinion
[Re: 1_WILD_RT]
#312325
05/09/09 12:12 AM
05/09/09 12:12 AM
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Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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k.i.s.s. Open them up & see what you see. Seal and boot kits for them are dirt cheap and a visual inspection will uncover most all issues & yes I did vote.
live every 24 hour block of time like it's your last day on earth
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Re: Poll for brake guys - NOS caliper opinion
[Re: Crizila]
#312329
05/09/09 09:50 AM
05/09/09 09:50 AM
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Joined: Sep 2007
Posts: 14,889
up yours
Supercuda
About to go away
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About to go away
Joined: Sep 2007
Posts: 14,889
up yours
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Let's see, last F body was buit in what? 81?
It's 2009, do math, that's 18 years.
Bet the rubber is bad. Might look ok but I would rebuild them anyway, ever hear of dryrot?
They say there are no such thing as a stupid question.
They say there is always the exception that proves the rule.
Don't be the exception.
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Re: Poll for brake guys - NOS caliper opinion
[Re: Supercuda]
#312330
05/09/09 11:49 AM
05/09/09 11:49 AM
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Joined: Jan 2004
Posts: 27,347
Today? Who Knows?
1_WILD_RT
Management Trainee
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Management Trainee
Joined: Jan 2004
Posts: 27,347
Today? Who Knows?
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Quote:
Let's see, last F body was buit in what? 81?
It's 2009, do math, that's 18 years.
Bet the rubber is bad. Might look ok but I would rebuild them anyway, ever hear of dryrot?
Go back to school.. Your math skills stink..  But your caliper knowledge is better.. 
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Re: Poll for brake guys - NOS caliper opinion
[Re: 1_WILD_RT]
#312331
05/09/09 12:49 PM
05/09/09 12:49 PM
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Joined: Jan 2003
Posts: 75,020
U.S.S.A.
JohnRR
I Win
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I Win
Joined: Jan 2003
Posts: 75,020
U.S.S.A.
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Quote:
Quote:
Let's see, last F body was buit in what? 81?
It's 2009, do math, that's 18 years.
Bet the rubber is bad. Might look ok but I would rebuild them anyway, ever hear of dryrot?
Go back to school.. Your math skills stink.. But your caliper knowledge is better..
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Re: Poll for brake guys - NOS caliper opinion
[Re: JohnRR]
#312332
05/10/09 06:43 PM
05/10/09 06:43 PM
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Joined: Sep 2007
Posts: 14,889
up yours
Supercuda
About to go away
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About to go away
Joined: Sep 2007
Posts: 14,889
up yours
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Sorry, I don't remember the 90's
29 years, lol
They say there are no such thing as a stupid question.
They say there is always the exception that proves the rule.
Don't be the exception.
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Re: Poll for brake guys - NOS caliper opinion
[Re: 68HemiB]
#312333
05/10/09 09:09 PM
05/10/09 09:09 PM
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Joined: Nov 2004
Posts: 9,312
SoCal
68HemiB
OP
master
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OP
master
Joined: Nov 2004
Posts: 9,312
SoCal
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Update: Person A: SEE! Only 30% of the poll respondants (after you take away the seed vote YOUR way), and none of the comments said go with them. Person B: Yeah, but they're your Internet buddies, so of course they're going to support your position. Person A: Not true. Nobody knew which position was mine. Besides, I know exactly ONE of the respondents personally, and most of them would rather bust my chops than come to my support. Person B: Okay, let's tear them down and have a look. So, we did. As it turns out, the quote below best describes the outcome (except his prediction on the speed at which two old guys and their beers can work): Quote:
Pulling the pistons out & visually inspecting them takes ten minutes per side.. If they look good you lost ten minutes, you can probably reuse the seals... If theres a problem I'd rather find it on the bench than on the road...
Photo number one is BEFORE:
Down to just a blue car now.
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Re: Poll for brake guys - NOS caliper opinion
[Re: 68HemiB]
#312334
05/10/09 09:11 PM
05/10/09 09:11 PM
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Joined: Nov 2004
Posts: 9,312
SoCal
68HemiB
OP
master
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OP
master
Joined: Nov 2004
Posts: 9,312
SoCal
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With 20-20 hindsight, I suppose they would have been good to go, once they freed up.
BUT we both sleep easier after investing the time.
Photo number 2 is immediately upon teardown, with no cleaning at all:
Down to just a blue car now.
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Re: Poll for brake guys - NOS caliper opinion
[Re: 68HemiB]
#312335
05/10/09 09:13 PM
05/10/09 09:13 PM
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Joined: Nov 2004
Posts: 9,312
SoCal
68HemiB
OP
master
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OP
master
Joined: Nov 2004
Posts: 9,312
SoCal
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The seals were supple and good as is.
Thanks to everyone who took the time to vote and/or comment.
Photo number final is a representative glimpse of the caliper innards, after a simple wipe with a clean rag:
Down to just a blue car now.
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They will most likely be pitted to a point that no ammount of clean-up will save them. Cores got my vote. They're a dime a dozen!
FWIW Glad the calipers looked good, sorry I wasted your time 
